Does the environment affect menopause? A review of the effects of endocrine disrupting chemicals on menopause

Estrogen replacement therapy reverses spatial memory loss and pyramidal cell neurodegeneration in the prefrontal cortex of lead-exposed ovariectomized Wistar rats

Background

Although menopause is a component of chronological aging, it may be induced by exposure to heavy metals like lead. Interestingly, lead exposure, just like the postmenopausal state, has been associated with spatial memory loss and neurodegeneration; however, the impact of hormone replacement therapy (HRT) on menopause and lead-induced spatial memory loss and neurodegeneration is yet to be reported.

Aim

The present study investigated the effect and associated mechanism of HRT on ovariectomized-driven menopausal state and lead exposure-induced spatial memory loss and neurodegeneration.

Materials and methods

Thirty adult female Wistar rats were randomized into 6 groups (n = 5 rats/group); the sham-operated vehicle-treated, ovariectomized (OVX), OVX + HRT, lead-exposed, OVX + lead, and OVX + Lead + HRT groups. Treatment was daily via gavage and lasted for 28 days.

Results

Ovariectomy and lead exposure impaired spatial memory deficit evidenced by a significant reduction in novel arm entry, time spent in the novel arm, alternation, time exploring novel and familiar objects, and discrimination index. These findings were accompanied by a marked distortion in the histology of the prefrontal cortex, and a decline in serum dopamine level and pyramidal neurons. In addition, ovariectomy and lead exposure induced metabolic disruption (as depicted by a marked rise in lactate level and lactate dehydrogenase and creatinine kinase activities), oxidative stress (evidenced by a significant increase in MDA level, and decrease in GSH level, and SOD and catalase activities), inflammation (as shown by significant upregulation of myeloperoxidase activity, and TNF-α and IL-1β), and apoptosis (evidenced by a rise in caspase 3 activity) of the prefrontal cortex. The observed biochemical and histological perturbations were attenuated by HRT.

Conclusions

This study revealed that HRT attenuated ovariectomy and lead-exposure-induced spatial memory deficit and pyramidal neurodegeneration by suppressing oxidative stress, inflammation, and apoptosis of the prefrontal cortex.

Mechanisms of mitochondrial dysfunction in ovarian aging and potential interventions

Mitochondria plays an essential role in regulating cellular metabolic homeostasis, proliferation/differentiation, and cell death. Mitochondrial dysfunction is implicated in many age-related pathologies. Evidence supports that the dysfunction of mitochondria and the decline of mitochondrial DNA copy number negatively affect ovarian aging. However, the mechanism of ovarian aging is still unclear. Treatment methods, including antioxidant applications, mitochondrial transplantation, emerging biomaterials, and advanced technologies, are being used to improve mitochondrial function and restore oocyte quality. This article reviews key evidence and research updates on mitochondrial damage in the pathogenesis of ovarian aging, emphasizing that mitochondrial damage may accelerate and lead to cellular senescence and ovarian aging, as well as exploring potential methods for using mitochondrial mechanisms to slow down aging and improve oocyte quality.

Analytical methods and biomonitoring results in hair for the assessment of exposure to endocrine-disrupting chemicals: A literature review

Endocrine-disrupting chemicals (EDC) are compounds that alter functions of the endocrine system due to their ability to mimic or antagonize endogenous hormones, or that alter their synthesis and metabolism, causing adverse health effects. Human biomonitoring (HBM) is a reliable method to assess human exposure to chemicals through measurement in human body fluids and tissues. It identifies new sources of exposure and determines their distribution, thereby enabling detection of the most exposed populations. Blood and urine are commonly used for HBM of EDC, but their interest is limited for compounds presenting short half-lives. Hair appears as an interesting alternative insofar as it provides a large exposure window. For the present study, we evaluated the relevance of hair in determining EDC exposure. With this in mind, we undertook a literature review focusing on the bioanalytical aspects and performances of methods developed to determine EDC in hair. The literature review was performed through methodical bibliographical research. Relevant articles were identified using two scientific databases: PubMed and Web of Science, with search equations built from a combination of keywords, MeSH terms and Boolean operators. The search strategy identified 2949 articles. After duplicates were removed, and following title, abstract, and full-text screenings, only 31 were included for qualitative synthesis. Hair collection was mainly performed in the back of the head and preparation involved two processes: cutting into small pieces or grounding to powder. The off-line LC-MS/MS method remains the main technique used to assess EDC through hair. Differences regarding the validation of analytical methods and interpretation of HBM results were highlighted, suggesting a need for international harmonisation to obtain reliable and comparable results. External contamination of hair was identified as a main limitation in the interpretation of results, highlighting the need to better understand EDC transfers through hair and to develop relevant hair decontamination processes.

Are the new phthalates safe? Evaluation of Diisononilphtalate (DINP) effects in porcine ovarian cell cultures

Phthalates are plasticizing chemicals, widely used in packaging materials and consumer products for several decades. These molecules have raised concerns because of their toxicity and their use have been restricted in several countries. Therefore, novel phthalates have been introduced. Among these, diisononilphtalate (DINP) is widely employed. However, its safety has not been properly addressed. Therefore, using a well validated granulosa cell model, collected from swine ovaries with a translational value, we studied potential DINP effects on important cellular functional parameters. In particular, we studied cell growth, steroidogenesis and redox status. Collected data showed that DINP stimulates (p < 0.05) cell growth, increases estrogen and inhibits progesterone production (p < 0.05), disrupts redox balance stimulating free radicals (p < 0.05) while reducing scavenger activities (p< 0.05). Taken together, DINP's impact on cultured swine granulosa cells provides cause for concern regarding its potential adverse effects on reproductive and endocrine functions.

Impact of climate and environmental change on the menopause

The huge impact of climate change on humankind is multidimensional, and includes direct and indirect challenges to the physical, psychological and socio-cultural wellbeing. Women may be more vulnerable to climate-sensitive diseases, but little attention has been paid to specific needs and challenges associated with the menopause transition. The increase in average and extreme temperatures may modulate the manifestation of vasomotor symptoms; in particular, environmental temperature and seasonality may affect hot flushes and night sweats. However, more research is needed to define the impact of climate-related factors among the determinants influencing the individual experience of menopause. In addition, increased exposure to environmental pollution and toxins may also have a role in the modulation of ovarian aging mechanisms, possibly influencing timing of menopause. Finally, both air pollution and menopause transition are associated with unfavorable modifications of cardio-metabolic, bone and cognitive health, and account should be taken of these in the evaluation of the individual woman's health vulnerabilities. Overall, the evidence reported in this narrative review supports the need for specific strategies aimed at reducing the burden of climate and environmental change on menopausal women. Healthcare providers should promote behavioral measures that reduce anthropogenic climate change and at the same time have a beneficial role on several domains of physical and psychological wellbeing. From this perspective, menopause represents a golden moment to implement virtuous behaviors that will benefit at the same time women's longevity and the planet.

Imprinting and Reproductive Health: A Toxicological Perspective

This overview discusses the role of imprinting in the development of an organism, and how exposure to environmental chemicals during fetal development leads to the physiological and biochemical changes that can have adverse lifelong effects on the health of the offspring. There has been a recent upsurge in the use of chemical products in everyday life. These chemicals include industrial byproducts, pesticides, dietary supplements, and pharmaceutical products. They mimic the natural estrogens and bind to estradiol receptors. Consequently, they reduce the number of receptors available for ligand binding. This leads to a faulty signaling in the neuroendocrine system during the critical developmental process of 'imprinting'. Imprinting causes structural and organizational differentiation in male and female reproductive organs, sexual behavior, bone mineral density, and the metabolism of exogenous and endogenous chemical substances. Several studies conducted on animal models and epidemiological studies provide profound evidence that altered imprinting causes various developmental and reproductive abnormalities and other diseases in humans. Altered metabolism can be measured by various endpoints such as the profile of cytochrome P-450 enzymes (CYP450's), xenobiotic metabolite levels, and DNA adducts. The importance of imprinting in the potentiation or attenuation of toxic chemicals is discussed.

Seahorse Male Pregnancy as a Model System to Study Pregnancy, Immune Adaptations, and Environmental Effects

Seahorses, together with sea dragons and pipefishes, belong to the Syngnathidae family of teleost fishes. Seahorses and other Syngnathidae species have a very peculiar feature: male pregnancy. Among different species, there is a gradation of paternal involvement in carrying for the offspring, from a simple attachment of the eggs to the skin surface, through various degrees of egg coverage by skin flaps, to the internal pregnancy within a brood pouch, which resembles mammalian uterus with the placenta. Because of the gradation of parental involvement and similarities to mammalian pregnancy, seahorses are a great model to study the evolution of pregnancy and the immunologic, metabolic, cellular, and molecular processes of pregnancy and embryo development. Seahorses are also very useful for studying the effects of pollutants and environmental changes on pregnancy, embryo development, and offspring fitness. We describe here the characteristics of seahorse male pregnancy, its regulatory mechanisms, the development of immune tolerance of the parent toward the allogeneic embryos, and the effects of environmental pollutants on pregnancy and embryo development.